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scsi: megaraid_sas: Remove IO buffer hole detection logic

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As blk_queue_virt_boundary() API in slave_configure ensures that no IOs
will come with holes/gaps. Hence, code logic to detect the holes/gaps in IO
buffer is not required.

Link: https://lore.kernel.org/r/20200508083838.22778-3-chandrakanth.patil@broadcom.com
Signed-off-by: Sumit Saxena <sumit.saxena@broadcom.com>
Signed-off-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Sumit Saxena 2020-05-08 14:08:35 +05:30 committed by Martin K. Petersen
parent 6c205a66d6
commit 84badfab0d
1 changed files with 0 additions and 58 deletions
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58
drivers/scsi/megaraid/megaraid_sas_fusion.c
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@ -2070,7 +2070,6 @@ static bool
megasas_is_prp_possible(struct megasas_instance *instance,
struct scsi_cmnd *scmd, int sge_count)
{
int i;
u32 data_length = 0;
struct scatterlist *sg_scmd;
bool build_prp = false;
@ -2099,63 +2098,6 @@ megasas_is_prp_possible(struct megasas_instance *instance,
build_prp = true;
}
/*
* Below code detects gaps/holes in IO data buffers.
* What does holes/gaps mean?
* Any SGE except first one in a SGL starts at non NVME page size
* aligned address OR Any SGE except last one in a SGL ends at
* non NVME page size boundary.
*
* Driver has already informed block layer by setting boundary rules for
* bio merging done at NVME page size boundary calling kernel API
* blk_queue_virt_boundary inside slave_config.
* Still there is possibility of IO coming with holes to driver because of
* IO merging done by IO scheduler.
*
* With SCSI BLK MQ enabled, there will be no IO with holes as there is no
* IO scheduling so no IO merging.
*
* With SCSI BLK MQ disabled, IO scheduler may attempt to merge IOs and
* then sending IOs with holes.
*
* Though driver can request block layer to disable IO merging by calling-
* blk_queue_flag_set(QUEUE_FLAG_NOMERGES, sdev->request_queue) but
* user may tune sysfs parameter- nomerges again to 0 or 1.
*
* If in future IO scheduling is enabled with SCSI BLK MQ,
* this algorithm to detect holes will be required in driver
* for SCSI BLK MQ enabled case as well.
*
*
*/
scsi_for_each_sg(scmd, sg_scmd, sge_count, i) {
if ((i != 0) && (i != (sge_count - 1))) {
if (mega_mod64(sg_dma_len(sg_scmd), mr_nvme_pg_size) ||
mega_mod64(sg_dma_address(sg_scmd),
mr_nvme_pg_size)) {
build_prp = false;
break;
}
}
if ((sge_count > 1) && (i == 0)) {
if ((mega_mod64((sg_dma_address(sg_scmd) +
sg_dma_len(sg_scmd)),
mr_nvme_pg_size))) {
build_prp = false;
break;
}
}
if ((sge_count > 1) && (i == (sge_count - 1))) {
if (mega_mod64(sg_dma_address(sg_scmd),
mr_nvme_pg_size)) {
build_prp = false;
break;
}
}
}
return build_prp;
}